patch(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | FILES | SEE ALSO | NOTES FOR PATCH SENDERS | DIAGNOSTICS | CAVEATS | COMPATIBILITY ISSUES | BUGS | COPYING | AUTHORS | COLOPHON

PATCH(1)                 General Commands Manual                 PATCH(1)

NAME         top

       patch - apply a diff file to an original

SYNOPSIS         top

       patch [options] [originalfile [patchfile]]

       but usually just

       patch -pnum <patchfile

DESCRIPTION         top

       patch takes a patch file patchfile containing a difference listing
       produced by the diff program and applies those differences to one
       or more original files, producing patched versions.  Normally the
       patched versions are put in place of the originals.  Backups can
       be made; see the -b or --backup option.  The names of the files to
       be patched are usually taken from the patch file, but if there's
       just one file to be patched it can be specified on the command
       line as originalfile.

       Upon startup, patch attempts to determine the type of the diff
       listing, unless overruled by a -c (--context), -e (--ed), -n
       (--normal), or -u (--unified) option.  Context diffs (old-style,
       new-style, and unified) and normal diffs are applied by the patch
       program itself, while ed diffs are simply fed to the ed(1) editor
       via a pipe.

       patch tries to skip any leading garbage, apply the diff, and then
       skip any trailing garbage.  Thus you could feed an email message
       containing a diff listing to patch, and it should work.  If the
       entire diff is indented by a consistent amount, if lines end in
       CRLF, or if a diff is encapsulated one or more times by prepending
       "- " to lines starting with "-" as specified by Internet RFC 934,
       this is taken into account.  After removing indenting or
       encapsulation, lines beginning with # are ignored, as they are
       considered to be comments.

       With context diffs, and to a lesser extent with normal diffs,
       patch can detect when the line numbers mentioned in the patch are
       incorrect, and attempts to find the correct place to apply each
       hunk of the patch.  As a first guess, it takes the line number
       mentioned for the hunk, plus or minus any offset used in applying
       the previous hunk.  If that is not the correct place, patch scans
       both forwards and backwards for a set of lines matching the
       context given in the hunk.  First patch looks for a place where
       all lines of the context match.  If no such place is found, and
       it's a context diff, and the maximum fuzz factor is set to 1 or
       more, then another scan takes place ignoring the first and last
       line of context.  If that fails, and the maximum fuzz factor is
       set to 2 or more, the first two and last two lines of context are
       ignored, and another scan is made.  (The default maximum fuzz
       factor is 2.)

       Hunks with less prefix context than suffix context (after applying
       fuzz) must apply at the start of the file if their first line
       number is 1.  Hunks with more prefix context than suffix context
       (after applying fuzz) must apply at the end of the file.

       If patch cannot find a place to install that hunk of the patch, it
       puts the hunk out to a reject file, which normally is the name of
       the output file plus a .rej suffix, or # if .rej would generate a
       file name that is too long (if even appending the single character
       # makes the file name too long, then # replaces the file name's
       last character).

       The rejected hunk comes out in unified or context diff format.  If
       the input was a normal diff, many of the contexts are simply null.
       The line numbers on the hunks in the reject file may be different
       than in the patch file: they reflect the approximate location
       patch thinks the failed hunks belong in the new file rather than
       the old one.

       As each hunk is completed, you are told if the hunk failed, and if
       so which line (in the new file) patch thought the hunk should go
       on.  If the hunk is installed at a different line from the line
       number specified in the diff, you are told the offset.  A single
       large offset may indicate that a hunk was installed in the wrong
       place.  You are also told if a fuzz factor was used to make the
       match, in which case you should also be slightly suspicious.  If
       the --verbose option is given, you are also told about hunks that
       match exactly.

       If no original file origfile is specified on the command line,
       patch tries to figure out from the leading garbage what the name
       of the file to edit is, using the following rules.

       First, patch takes an ordered list of candidate file names as
       follows:

         •  If the header is that of a context diff, patch takes the old
            and new file names in the header.  A name is ignored if it
            does not have enough slashes to satisfy the -pnum or
            --strip=num option.  The name /dev/null is also ignored.

         •  If there is an Index: line in the leading garbage and if
            either the old and new names are both absent or if patch is
            conforming to POSIX, patch takes the name in the Index: line.

         •  For the purpose of the following rules, the candidate file
            names are considered to be in the order (old, new, index),
            regardless of the order that they appear in the header.

       Then patch selects a file name from the candidate list as follows:

         •  If some of the named files exist, patch selects the first
            name if conforming to POSIX, and the best name otherwise.

         •  If patch is not ignoring RCS, ClearCase, Perforce, and SCCS
            (see the -g num or --get=num option), and no named files
            exist but an RCS, ClearCase, Perforce, or SCCS master is
            found, patch selects the first named file with an RCS,
            ClearCase, Perforce, or SCCS master.

         •  If no named files exist, no RCS, ClearCase, Perforce, or SCCS
            master was found, some names are given, patch is not
            conforming to POSIX, and the patch appears to create a file,
            patch selects the best name requiring the creation of the
            fewest directories.

         •  If no file name results from the above heuristics, you are
            asked for the name of the file to patch, and patch selects
            that name.

       To determine the best of a nonempty list of file names, patch
       first takes all the names with the fewest path name components; of
       those, it then takes all the names with the shortest basename; of
       those, it then takes all the shortest names; finally, it takes the
       first remaining name.

       Additionally, if the leading garbage contains a Prereq: line,
       patch takes the first word from the prerequisites line (normally a
       version number) and checks the original file to see if that word
       can be found.  If not, patch asks for confirmation before
       proceeding.

       The upshot of all this is that you should be able to run something
       like the following shell command:

              patch -d /usr/src/local/blurfl

       and patch a file in the blurfl directory directly from a patch
       that is read from standard input.

       If the patch file contains more than one patch, patch tries to
       apply each of them as if they came from separate patch files.
       This means, among other things, that it is assumed that the name
       of the file to patch must be determined for each diff listing, and
       that the garbage before each diff listing contains interesting
       things such as file names and revision level, as mentioned
       previously.

OPTIONS         top

       -b  or  --backup
          Make backup files.  That is, when patching a file, rename or
          copy the original instead of removing it.  See the -V or
          --version-control option for details about how backup file
          names are determined.

       --backup-if-mismatch
          Back up a file if the patch does not match the file exactly and
          if backups are not otherwise requested.  This is the default
          unless patch is conforming to POSIX.

       --no-backup-if-mismatch
          Do not back up a file if the patch does not match the file
          exactly and if backups are not otherwise requested.  This is
          the default if patch is conforming to POSIX.

       -B pref  or  --prefix=pref
          Use the simple method to determine backup file names (see the
          -V method or --version-control method option), and append pref
          to a file name when generating its backup file name.  For
          example, with -B /junk/ the simple backup file name for
          src/patch/util.c is /junk/src/patch/util.c.

       --binary
          Write all files in binary mode, except for standard output and
          /dev/tty.  When reading, disable the heuristic for transforming
          CRLF line endings into LF line endings.  This option is needed
          on POSIX systems when applying patches generated on non-POSIX
          systems to non-POSIX files.  (On POSIX systems, file reads and
          writes never transform line endings. On Windows, reads and
          writes do transform line endings by default, and patches should
          be generated by diff --binary when line endings are
          significant.)

       -c  or  --context
          Interpret the patch file as a ordinary context diff.

       -d dir  or  --directory=dir
          Change to the directory dir immediately, before doing anything
          else.

       -D define  or  --ifdef=define
          Use the #ifdef ... #endif construct to mark changes, with
          define as the differentiating symbol.

       --dry-run
          Print the results of applying the patches without actually
          changing any files.

       -e  or  --ed
          Interpret the patch file as an ed script.

       -E  or  --remove-empty-files
          Remove output files that are empty after the patches have been
          applied.  Normally this option is unnecessary, since patch can
          examine the timestamps on the header to determine whether a
          file should exist after patching.  However, if the input is not
          a context diff or if patch is conforming to POSIX, patch does
          not remove empty patched files unless this option is given.
          When patch removes a file, it also attempts to remove any empty
          ancestor directories.

       -f  or  --force
          Assume that the user knows exactly what he or she is doing, and
          do not ask any questions.  Skip patches whose headers do not
          say which file is to be patched; patch files even though they
          have the wrong version for the Prereq: line in the patch; and
          assume that patches are not reversed even if they look like
          they are.  This option does not suppress commentary; use -s for
          that.

       -F num  or  --fuzz=num
          Set the maximum fuzz factor.  This option only applies to diffs
          that have context, and causes patch to ignore up to that many
          lines of context in looking for places to install a hunk.  Note
          that a larger fuzz factor increases the odds of a faulty patch.
          The default fuzz factor is 2.  A fuzz factor greater than or
          equal to the number of lines of context in the context diff,
          ordinarily 3, ignores all context.

       -g num  or  --get=num
          This option controls patch's actions when a file is under RCS
          or SCCS control, and does not exist or is read-only and matches
          the default version, or when a file is under ClearCase or
          Perforce control and does not exist.  If num is positive, patch
          gets (or checks out) the file from the revision control system;
          if zero, patch ignores RCS, ClearCase, Perforce, and SCCS and
          does not get the file; and if negative, patch asks the user
          whether to get the file.  The default value of this option is
          given by the value of the PATCH_GET environment variable if it
          is set; if not, the default value is zero.

       --help
          Print a summary of options and exit.

       -i patchfile  or  --input=patchfile
          Read the patch from patchfile.  If patchfile is -, read from
          standard input, the default.

       -l  or  --ignore-whitespace
          Match patterns loosely, in case tabs or spaces have been munged
          in your files.  Any sequence of one or more blanks in the patch
          file matches any sequence in the original file, and sequences
          of blanks at the ends of lines are ignored.  Normal characters
          must still match exactly.  Each line of the context must still
          match a line in the original file.

       --merge or --merge=merge or --merge=diff3
          Merge a patch file into the original files similar to diff3(1)
          or merge(1).  If a conflict is found, patch outputs a warning
          and brackets the conflict with <<<<<<< and >>>>>>> lines.  A
          typical conflict will look like this:

              <<<<<<<
              lines from the original file
              |||||||
              original lines from the patch
              =======
              new lines from the patch
              >>>>>>>

          The optional argument of --merge determines the output format
          for conflicts: the diff3 format shows the ||||||| section with
          the original lines from the patch; in the merge format, this
          section is missing.  The merge format is the default.

          This option implies --forward and does not take the --fuzz=num
          option into account.

       -n  or  --normal
          Interpret the patch file as a normal diff.

       -N  or  --forward
          When a patch does not apply, patch usually checks if the patch
          looks like it has been applied already by trying to reverse-
          apply the first hunk.  The --forward option prevents that.  See
          also -R.

       -o outfile  or  --output=outfile
          Send output to outfile instead of patching files in place.  Do
          not use this option if outfile is one of the files to be
          patched.  When outfile is -, send output to standard output,
          and send any messages that would usually go to standard output
          to standard error.

       -pnum  or  --strip=num
          Strip the smallest prefix containing num leading slashes from
          each file name found in the patch file.  A sequence of one or
          more adjacent slashes is counted as a single slash.  This
          controls how file names found in the patch file are treated, in
          case you keep your files in a different directory than the
          person who sent out the patch.  For example, supposing the file
          name in the patch file was

          /u/howard/src/blurfl/blurfl.c

       setting -p0 gives the entire file name unmodified, -p1 gives

          u/howard/src/blurfl/blurfl.c

       without the leading slash, -p4 gives

          blurfl/blurfl.c

       and not specifying -p at all just gives you blurfl.c.  Whatever
       you end up with is looked for either in the current directory, or
       the directory specified by the -d option.

       --posix
          Conform more strictly to the POSIX standard, as follows.

         •  Take the first existing file from the list (old, new, index)
            when intuiting file names from diff headers.

         •  Do not remove files that are empty after patching.

         •  Do not ask whether to get files from RCS, ClearCase,
            Perforce, or SCCS.

         •  Require that all options precede the files in the command
            line.

         •  Do not backup files when there is a mismatch.

       --quoting-style=word
          Use style word to quote output names.  The word should be one
          of the following:

          literal
                 Output names as-is.

          shell  Quote names for the shell if they contain shell
                 metacharacters or would cause ambiguous output.

          shell-always
                 Quote names for the shell, even if they would normally
                 not require quoting.

          c      Quote names as for a C language string.

          escape Quote as with c except omit the surrounding double-quote
                 characters.

          You can specify the default value of the --quoting-style option
          with the environment variable QUOTING_STYLE.  If that
          environment variable is not set, the default value is shell.

       -r rejectfile  or  --reject-file=rejectfile
          Put rejects into rejectfile instead of the default .rej file.
          When rejectfile is -, discard rejects.

       -R  or  --reverse
          Assume that this patch was created with the old and new files
          swapped.  (Yes, I'm afraid that does happen occasionally, human
          nature being what it is.)  patch attempts to swap each hunk
          around before applying it.  Rejects come out in the swapped
          format.  The -R option does not work with ed diff scripts
          because there is too little information to reconstruct the
          reverse operation.

          If the first hunk of a patch fails, patch reverses the hunk to
          see if it can be applied that way.  If it can, you are asked if
          you want to have the -R option set.  If it can't, the patch
          continues to be applied normally.  (Note: this method cannot
          detect a reversed patch if it is a normal diff and if the first
          command is an append (i.e. it should have been a delete) since
          appends always succeed, due to the fact that a null context
          matches anywhere.  Luckily, most patches add or change lines
          rather than delete them, so most reversed normal diffs begin
          with a delete, which fails, triggering the heuristic.)

       --read-only=behavior
          Behave as requested when trying to modify a read-only file:
          ignore the potential problem, warn about it (the default), or
          fail.

       --reject-format=format
          Produce reject files in the specified format (either context or
          unified).  Without this option, rejected hunks come out in
          unified diff format if the input patch was of that format,
          otherwise in ordinary context diff form.

       -s  or  --silent  or  --quiet
          Work silently, unless an error occurs.

       --follow-symlinks
          When looking for input files, follow symbolic links.  Replaces
          the symbolic links, instead of modifying the files the symbolic
          links point to.  Git-style patches to symbolic links will no
          longer apply.  This option exists for backwards compatibility
          with previous versions of patch; its use is discouraged.

       -t  or  --batch
          Suppress questions like -f, but make some different
          assumptions: skip patches whose headers do not contain file
          names (the same as -f); skip patches for which the file has the
          wrong version for the Prereq: line in the patch; and assume
          that patches are reversed if they look like they are.

       -T  or  --set-time
          Set the modification and access times of patched files from
          timestamps given in context diff headers.  Unless specified in
          the timestamps, assume that the context diff headers use local
          time.

          Use of this option with timestamps that do not include time
          zones is not recommended, because patches using local time
          cannot easily be used by people in other time zones, and
          because local timestamps are ambiguous when local clocks move
          backwards during daylight-saving time adjustments.  Make sure
          that timestamps include time zones, or generate patches with
          UTC and use the -Z or --set-utc option instead.

       -u  or  --unified
          Interpret the patch file as a unified context diff.

       -v  or  --version
          Print out patch's revision header and patch level, and exit.

       -V method  or  --version-control=method
          Use method to determine backup file names.  The method can also
          be given by the PATCH_VERSION_CONTROL (or, if that's not set,
          the VERSION_CONTROL) environment variable, which is overridden
          by this option.  The method does not affect whether backup
          files are made; it affects only the names of any backup files
          that are made.

          The value of method is like the GNU Emacs version-control
          variable; patch also recognizes synonyms that are more
          descriptive.  The valid values for method are (unique
          abbreviations are accepted):

          existing  or  nil
             Make numbered backups of files that already have them,
             otherwise simple backups.  This is the default.

          numbered  or  t
             Make numbered backups.  The numbered backup file name for F
             is F.~N~ where N is the version number.

          simple  or  never
             Make simple backups.  The -B or --prefix, -Y or
             --basename-prefix, and -z or --suffix options specify the
             simple backup file name.  If none of these options are
             given, then a simple backup suffix is used; it is the value
             of the SIMPLE_BACKUP_SUFFIX environment variable if set, and
             is .orig otherwise.

          With numbered or simple backups, if the backup file name is too
          long, the backup suffix ~ is used instead; if even appending ~
          would make the name too long, then ~ replaces the last
          character of the file name.

       --verbose
          Output extra information about the work being done.

       -x num  or  --debug=num
          Set internal debugging flags of interest only to patch
          patchers.

       -Y pref  or  --basename-prefix=pref
          Use the simple method to determine backup file names (see the
          -V method or --version-control method option), and prefix pref
          to the basename of a file name when generating its backup file
          name.  For example, with -Y .del/ the simple backup file name
          for src/patch/util.c is src/patch/.del/util.c.

       -z suffix  or  --suffix=suffix
          Use the simple method to determine backup file names (see the
          -V method or --version-control method option), and use suffix
          as the suffix.  For example, with -z - the backup file name for
          src/patch/util.c is src/patch/util.c-.

       -Z  or  --set-utc
          Set the modification and access times of patched files from
          timestamps given in context diff headers. Unless specified in
          the timestamps, assume that the context diff headers use
          Coordinated Universal Time (UTC, often known as GMT).  Also see
          the -T or --set-time option.

          The -Z or --set-utc and -T or --set-time options normally
          refrain from setting a file's time if the file's original time
          does not match the time given in the patch header, or if its
          contents do not match the patch exactly.  However, if the -f or
          --force option is given, the file time is set regardless.

          Due to the limitations of diff output format, these options
          cannot update the times of files whose contents have not
          changed.  Also, if you use these options, you should remove
          (e.g. with make clean) all files that depend on the patched
          files, so that later invocations of make do not get confused by
          the patched files' times.

ENVIRONMENT         top

       PATCH_GET
          This specifies whether patch gets missing or read-only files
          from RCS, ClearCase, Perforce, or SCCS by default; see the -g
          or --get option.

       POSIXLY_CORRECT
          If set, patch conforms more strictly to the POSIX standard by
          default: see the --posix option.

       QUOTING_STYLE
          Default value of the --quoting-style option.

       SIMPLE_BACKUP_SUFFIX
          Extension to use for simple backup file names instead of .orig.

       TMPDIR, TMP, TEMP
          Directory to put temporary files in; patch uses the first
          environment variable in this list that is set.  If none are
          set, the default is system-dependent; it is normally /tmp on
          Unix hosts.

       VERSION_CONTROL or PATCH_VERSION_CONTROL
          Selects version control style; see the -v or --version-control
          option.

FILES         top

       $TMPDIR/p*
          temporary files

       /dev/tty
          controlling terminal; used to get answers to questions asked of
          the user

SEE ALSO         top

       diff(1), ed(1), merge(1).

       Marshall T. Rose and Einar A. Stefferud, Proposed Standard for
       Message Encapsulation, Internet RFC 934
       <https://datatracker.ietf.org/doc/html/rfc934> (1985-01).

NOTES FOR PATCH SENDERS         top

       There are several things you should bear in mind if you are going
       to be sending out patches.

       Create your patch systematically.  When using a version control
       system this should be easy; for example, with Git you can use git
       diff.  Otherwise, a good method is the command diff -Naur old new
       where old and new identify the old and new directories.  The names
       old and new should not contain any slashes.

       If the patch should communicate file timestamps as well as file
       contents, its diff commands' headers should have dates and times
       in Universal Time using traditional Unix format, so that patch
       recipients can use the -Z or --set-utc option.  Here is an example
       command to generate such headers, using Bourne shell syntax:

              LC_ALL=C TZ=UTC0 diff -Naur myprog-2.7 myprog-2.8

       Tell your recipients how to apply the patch by telling them which
       directory to cd to, and which patch options to use.  The option
       string -Np1 is recommended.  Test your procedure by pretending to
       be a recipient and applying your patch to a copy of the original
       files.

       You can save people a lot of grief by keeping a patchlevel.h file
       which is patched to increment the patch level as the first diff in
       the patch file you send out.  If you put a Prereq: line in with
       the patch, it won't let them apply patches out of order without
       some warning.

       You can create a file by sending out a diff that compares
       /dev/null or an empty file dated the Epoch (1970-01-01 00:00:00
       UTC) to the file you want to create.  This only works if the file
       you want to create doesn't exist already in the target directory.
       Conversely, you can remove a file by sending out a context diff
       that compares the file to be deleted with an empty file dated the
       Epoch.  The file will be removed unless patch is conforming to
       POSIX and the -E or --remove-empty-files option is not given.  An
       easy way to generate patches that create and remove files is to
       use GNU diff's -N or --new-file option.

       If the recipient is supposed to use the -pN option, do not send
       output that looks like this:

              diff -Naur v2.0.29/prog/README prog/README
              --- v2.0.29/prog/README   Mon Mar 10 15:13:12 2024
              +++ prog/README   Mon Mar 17 14:58:22 2024

       because the two file names have different numbers of slashes, and
       different versions of patch interpret the file names differently.
       To avoid confusion, send output that looks like this instead:

              diff -Naur v2.0.29/prog/README v2.0.30/prog/README
              --- v2.0.29/prog/README   Mon Mar 10 15:13:12 2024
              +++ v2.0.30/prog/README   Mon Mar 17 14:58:22 2024

       Avoid sending patches that compare backup file names like
       README.orig, since this might confuse patch into patching a backup
       file instead of the real file.  Instead, send patches that compare
       the same base file names in different directories, e.g. old/README
       and new/README.

       Take care not to send out reversed patches, since it makes people
       wonder whether they already applied the patch.

       Try not to have your patch modify derived files (e.g. the file
       configure where there is a line configure: configure.ac in your
       makefile), since the recipient should be able to regenerate the
       derived files anyway.  If you must send diffs of derived files,
       generate the diffs using UTC, have the recipients apply the patch
       with the -Z or --set-utc option, and have them remove any
       unpatched files that depend on patched files (e.g. with
       make clean).

       While you may be able to get away with putting 582 diff listings
       into one file, it may be wiser to group related patches into
       separate files in case something goes haywire.

DIAGNOSTICS         top

       Diagnostics generally indicate that patch couldn't parse your
       patch file.

       If the --verbose option is given, the message Hmm... indicates
       that there is unprocessed text in the patch file and that patch is
       attempting to intuit whether there is a patch in that text and, if
       so, what kind of patch it is.

       patch's exit status is 0 if all hunks are applied successfully, 1
       if some hunks cannot be applied or there were merge conflicts, and
       2 if there is more serious trouble.  When applying a set of
       patches in a loop it behooves you to check this exit status so you
       don't apply a later patch to a partially patched file.

CAVEATS         top

       Context diffs cannot reliably represent the creation or deletion
       of empty files, empty directories, or special files such as
       symbolic links.  Nor can they represent changes to file metadata
       like ownership, permissions, or whether one file is a hard link to
       another.  If changes like these are also required, separate
       instructions (e.g. a shell script) to accomplish them should
       accompany the patch.

       patch cannot tell if the line numbers are off in an ed script, and
       can detect bad line numbers in a normal diff only when it finds a
       change or deletion.  A context diff using fuzz factor 3 may have
       the same problem.  You should probably do a context diff in these
       cases to see if the changes made sense.  Of course, compiling
       without errors is a pretty good indication that the patch worked,
       but not always.

       patch usually produces the correct results, even when it has to do
       a lot of guessing.  However, the results are guaranteed to be
       correct only when the patch is applied to exactly the same version
       of the file that the patch was generated from.

COMPATIBILITY ISSUES         top

       The POSIX standard specifies behavior that differs from GNU patch.

         •  In POSIX patch when -b is not used, backups are not made even
            when there is a mismatch.  In GNU patch, this behavior is
            enabled with the --no-backup-if-mismatch option, or by
            conforming to POSIX with the --posix option or by setting the
            POSIXLY_CORRECT environment variable.

         •  When intuiting the name of the file to be patched from the
            patch header, patch uses a complicated method that is
            optionally POSIX-conforming.  The method is equivalent to
            POSIX if the file names in the context diff header and the
            Index: line are all identical after prefix-stripping.  Your
            patch is normally compatible if each header's file names all
            contain the same number of slashes.

         •  Limit yourself to the following options when sending
            instructions meant to be executed by anyone running GNU patch
            or a patch that conforms to POSIX.  Spaces are optional in
            the following list.

               -b
               -c
               -d dir
               -D define
               -e
               -i patchfile
               -l
               -n
               -N
               -o outfile
               -p num
               -R
               -r rejectfile
               -u

BUGS         top

       Please report bugs via email to <bug-patch@gnu.org>.

       If code has been duplicated (for instance with #ifdef OLDCODE ...
       #else ... #endif), patch is incapable of patching both versions,
       and, if it works at all, will likely patch the wrong one, and tell
       you that it succeeded to boot.

       If you apply a patch you've already applied, patch thinks it is a
       reversed patch, and offers to un-apply the patch.  This could be
       construed as a feature.

       Computing how to merge a hunk is significantly harder than using
       the standard fuzzy algorithm.  Bigger hunks, more context, a
       bigger offset from the original location, and a worse match all
       slow the algorithm down.

COPYING         top

       Copyright © 1989–2025 Free Software Foundation, Inc.
       Copyright © 1984–1986, 1988 Larry Wall.

       Permission is granted to make and distribute verbatim copies of
       this manual provided the copyright notice and this permission
       notice are preserved on all copies.

       Permission is granted to copy and distribute modified versions of
       this manual under the conditions for verbatim copying, provided
       that the entire resulting derived work is distributed under the
       terms of a permission notice identical to this one.

       Permission is granted to copy and distribute translations of this
       manual into another language, under the above conditions for
       modified versions, except that this permission notice may be
       included in translations approved by the copyright holders instead
       of in the original English.

AUTHORS         top

       Larry Wall wrote the original version of patch.  Paul Eggert
       removed patch's arbitrary limits; added support for binary files,
       setting file times, and deleting files; and made it conform better
       to POSIX.  Other contributors include Wayne Davison, who added
       unidiff support, and David MacKenzie, who added configuration and
       backup support.  Andreas Gruenbacher added support for merging.

COLOPHON         top

       This page is part of the patch (GNU patch) project.  Information
       about the project can be found at 
       ⟨http://savannah.gnu.org/projects/patch/⟩.  If you have a bug
       report for this manual page, see
       ⟨http://savannah.gnu.org/bugs/?group=patch⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨git://git.savannah.gnu.org/patch.git⟩ on 2025-02-02.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2025-01-08.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there is
       a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

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